RE: [amsat-bb] A new trakbox like device?

["Andrew Rich" <vk4tec@xxxxxxxxxxxxxxxxx>]

Bob,

I tried the time method and it got so far off after so many moves I gave up
in dispair.

I came to the conclusion that a feedback system would be far better, using a
simple PIC cct.

-----------------------------------------
Andrew Rich
Amateur radio callsign VK4TEC
email: vk4tec@tech-software.net <mailto:vk4tec@tech-software.net>
web: http://www.tech-software.net
Brisbane AUSTRALIA



-----Original Message-----
From: Robert Bruninga [mailto:bruninga@usna.edu]
Sent: Wednesday, 26 April 2006 10:48 PM
To: amsat-bb@amsat.org; dc@dcarr.org
Subject: Re: [amsat-bb] A new trakbox like device?


David,
In my (humble) opinion, a unique and very practical
thing you could do with your tracking code
microcontroller would be to implement the cheap
2 bit  (go left or go right) interface to the radio-shack
common $69 TV rotator like is in APRStk.

A TV rotator is perfect for all the currrent LEO
satellties and Elevation simply is not needed.
Fixe elevation of about 10 degrees and a small
beam will give nearly constant 10 dB gain from the
horizon to overhead 98% of all pass tiimes...
See the table on:

http://www.ew.usna.edu/~bruninga/rotator1.html

The two bits just tell the rotator to go left or right
by TIME duration.  Most TV rotators are 1 RPM.
A 1 second pulse will move the rotator 6 degrees.

There is NO FEEDBACK system required.  It is
just plug and play.  The KEY is that whenever a
pass goes through SOUTH (where you locate
the mechanical stop), then the system is
automatically re-calibrated.  Further, in my code
whenever a pass ends anywhere within 45 deg
of south, and there are no other satellites in
view, then it will drive the rotator TO SOUTH
to again, re-calibrate.

It is simple, cheap, and it always works,  does not
need any mods to the Radio Shack (or any other TV
rotator) other than wiring in the LEFT and
RIGHT contact closures.  Anda again, Elevation
just is NOT required for any existing LEO
satellite...

I would NOT recoemmend using a HUGE OSCAR class
antenna with a very narrow beam (which is not needed
anyway for LEO's).  It is better to use a small or
medium beam which has a more forgiving beamwidth..

Bob, WB4APR



>>> David Carr <dc@dcarr.org> 04/26/06 6:07 AM >>>
    I was playing with some satellite prediction code yesterday that
could be fairly easily ported to a 32 bit microcontroller.  That got me
to wondering if there would still be any interest in a trakbox-like
stand alone rotator controller.

What applications would such a device have?  Should it control radios as
well?  I'm curious to see if laptop computers have supplanted the need
for such a device.  Ideas and comments welcome...

73s,
David Carr
KD5QGR
----
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
----
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
----
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org